Stackable electronic component

ABSTRACT

An embodiment of an electronic component includes a circuit element disposed within a package, which includes a surface and at least one standoff protruding from the surface. For example, where the circuit element is an inductor in a power supply, the standoff may allow one to mount the inductor component over another component, such as a transistor component. Therefore, the layout area of such a power supply may be smaller than the layout area of a power supply in which the inductor and transistor components are mounted side by side.

CLAIM OF PRIORITY

This application is a Divisional of U.S. Non-Provisional application Ser. No. 12/202,985 filed on Sep. 2, 2008, which claims the benefit of U.S. Provisional Application Ser. No. 60/967,151 filed on Aug. 31, 2007, which is incorporated by reference.

SUMMARY

This Summary is provided to introduce, in a simplified form, a selection of concepts that are further described below in the Detailed Description.

This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

An embodiment of an electronic component includes a package and a circuit element disposed within the package, which includes a surface and a standoff protruding from the surface.

For example, where the circuit element is an inductor in a power supply, the standoff may allow one to mount the inductor component over another component, such as a transistor component. Therefore, the layout area of such a power supply may be smaller than the layout area of a power supply in which the inductor and transistor components are mounted side by side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an embodiment of a power supply having one or more phases.

FIGS. 2A-2C are respective side, bottom, and schematic views of an embodiment of a transistor component that may be used in the power supply of FIG. 1.

FIG. 3A is a perspective view of a portion of an embodiment of the power supply of FIG. 1, the portion including an inductor component stacked over transistor components that are similar to the transistor component of FIGS. 2A-2C.

FIG. 3B is a side view of the power-supply portion of FIG. 3A.

FIG. 4 is a side view of another embodiment of the power-supply portion of FIGS. 3A and 3B.

FIGS. 5 and 6 are side views of respective other embodiments of the power-supply portion of FIGS. 3A and 3B.

FIG. 7 is a perspective view of a portion of another embodiment of a power supply according to the schematic diagram of FIG. 1.

FIG. 8 is a block diagram of an embodiment of a computer system having one or more power supplies that include one or more of the power-supply portions of FIGS. 3-6.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of an embodiment of a power supply 10, here a buck converter, which provides a regulated output voltage V_(out) and which includes one or more phase paths (alternatively “phases”) 12 ₁-12 _(n) each having a respective high-side drive transistor 14 ₁-14 _(n), a respective low-side drive transistor 16-16 _(n), and a respective inductor L₁-L_(n). As discussed below in conjunction with FIGS. 3-7, the inductors L₁-L_(n) may be part of an inductor component 18, which may be stackable over one or more other components such as components that include the transistors 14 and 16. Such stacking of components may reduce the area occupied by the power supply 10 as compared to prior power supplies in which the components are not stacked, but are instead laid out side by side.

In addition to the transistors 14 and 16 and the inductor component 18, the power supply 10 includes current sensors 20 ₁-20 _(n), a power-supply controller 22, a filter capacitor 24, and an optional filter inductor 26. An inductor L and the high-side and low-side transistors 14 and 16 coupled to the inductor at a phase intermediate node INT compose a respective phase 12. For example, the inductor L₁ and the transistors 14 ₁ and 16 ₁ compose the phase 12 ₁.

The high-side transistors 14 ₁-14 _(n), which are each switched “on” and “off” by the controller 22, are power NMOS transistors that are respectively coupled between input voltages VIN₁-VIN_(n) and the nodes INT₁-INT_(n). Alternatively, the transistors 14 ₁-14 _(n) may be other than power NMOS transistors, and may be coupled to a common input voltage. Moreover, the transistors 14 ₁-14 _(n) may be integrated on the same die as the controller 22, may be integrated on a same die that is separate from the die on which the controller is integrated, or may be disposed on discrete transistor components as discussed below in conjunction with FIGS. 2A-7.

Similarly, the low-side transistors 16 ₁-16 _(n), which are each switched on and off by the controller 22, are power NMOS transistors that are respectively coupled between low-side voltages VL₁-VL_(n) and the nodes INT₁-INT_(n) of the inductors L₁-L_(n). Alternatively, the transistors 16 ₁-16 _(n) may be other than power NMOS transistors, and may be coupled to a common low-side voltage such as ground. Moreover, the transistors 16 ₁-16 _(n) may be integrated on the same die as the controller 22, may be integrated on a same die that is separate from the die on which the controller is integrated, may be integrated on a same die as the high-side transistors 16 ₁-16 _(n), may be integrated on respective dies with the corresponding high-side transistors 16 ₁-16 _(n) (e.g., transistors 14 ₁ and 16 ₁ on a first die, transistors 14 ₂ and 16 ₂ on a second die, and so on), or may be disposed on discrete transistor components as discussed below in conjunction with FIGS. 2A-7.

The inductors L₁-L_(n) of the inductor component 18 may be magnetically coupled to one another, may be magnetically uncoupled from one another, or some of the inductors may be magnetically coupled and others of the inductors may be magnetically uncoupled. Power supplies incorporating magnetically coupled inductors, magnetically uncoupled inductors, or both magnetically coupled and magnetically uncoupled inductors, are discussed in the following U.S. patent applications, which are incorporated by reference: application Ser. No. 11/903,185 filed Sep. 19, 2007, application Ser. Nos. 12/136,014, 12/136,018, 12/136,023 all filed Jun. 9, 2008, and application Ser. No. 12/189,112 filed Aug. 8, 2008.

The current sensors 20 ₁-20 _(n) respectively generate sense signals I_(FB1)-I_(FBn), which respectively represent the phase currents i₁-i_(n). For example, each of the signals I_(FB1)-I_(FBn) may be a respective voltage that has substantially the same signal phase as the corresponding phase current i and that has an amplitude that is substantially proportional to the amplitude of the corresponding phase current.

The controller 22 may be any type of controller suitable for use in a power supply, is supplied by voltages VDD_(controller) and VSS_(controller), and receives the regulated output voltage V_(out), a reference voltage V_(ref), and the sense signals I_(FB1)-I_(FBn), which are fed back to the controller from the current sensors 20 ₁-20 _(n), respectively. The controller 22 may use V_(ref) and the fed back V_(out) and I_(FB1)-I_(FBn) to conventionally regulate V_(out) to a specified value.

The filter capacitor 24 is coupled between the regulated output voltage V_(out) and a voltage VSS_(cap), and works in concert with the inductors L₁-L_(n) and the optional filter inductor 26 (if present) to maintain the amplitude of the steady-state ripple-voltage component of V_(out) within a desired range, which may be on the order of hundreds of microvolts (μV) to tens of millivolts (mV). Although only one filter capacitor 24 is shown, the power supply 10 may include multiple filter capacitors coupled in electrical parallel. Furthermore, multiple serially coupled LC filter stages (each stage would be similar to the stage formed by the optional filter inductor 26 and the filter capacitor 24) may be disposed between V_(out) and the inductors L₁-L_(n), and the feedback to the controller 22 may be taken from V_(out) (the output of the last filter stage) or from any one of the previous filter stages. Moreover, VSS_(cap) may be equal to VSS_(controller) and to VL₁-VL_(n); for example, all of these voltages may equal ground.

The optional filter inductor 26 may be omitted from the power supply 10. For example, the filter inductor 26 may be omitted if the inductors L₁-L_(n) are not magnetically coupled to one another, or if the inductors L₁-L_(n) are magnetically coupled to one another and the respective leakage inductances of the inductors L₁-L_(n) are sufficient to perform the specified inductive filtering function. Omitting the filter inductor 26 may reduce the size (e.g., the layout area) and component count of the power supply 10, and may eliminate a component through which the total supply current (i.e., i₁+i₂+. . . +i_(n)) flows.

The power supply 10 may provide the regulated voltage V_(out) to a load 28, such as a microprocessor or other electronic load.

Still referring to FIG. 1, alternate embodiments of the power supply 10 are contemplated. For example, although described as a single-phase or multiphase buck converter, the power supply 10 may be any other type of single-phase or multiphase power supply. Furthermore, the current sensors 20 ₁-20 _(n) may be omitted.

FIGS. 2A-2C are respective side, bottom, and schematic views of an embodiment of a transistor component 30, which includes a low-profile surface-mount package 32 and an NMOS transistor 34 such as one of the transistors 14 ₁-14 _(n) and 16 ₁-16 _(n) of FIG. 1. D, S, and G respectively indicate the drain, source, and gate leads of the transistor 34, and, in one embodiment, the package length I, width w, and height h have approximately the following respective values: 6.15 millimeters (mm), 5.15 mm, and 1.1 mm. As discussed below in conjunction with FIGS. 3-7, one or more transistor components like the transistor component 30 may be used to implement the transistors 14 ₁-14 n and 16 ₁-16 _(n) in a physical implementation of the power supply 10 of FIG. 1.

Still referring to FIGS. 2A-2C, alternate embodiments of the transistor component 30 are contemplated. For example, although described as including one NMOS transistor 34, the component 30 may include multiple transistors, one or more transistors of different types (e.g., bipolar), or other electronic components such as one or more diodes.

FIG. 3A is a perspective view of a portion 40 of an embodiment of the power supply 10 of FIG. 1, in which the inductor component 18 is stacked over one or more transistor components to reduce the layout area occupied by the power supply.

FIG. 3B is a side view of the portion 40 of FIG. 3A.

Referring to FIGS. 3A and 3B, the power-supply portion 40 includes transistor components 42 ₁-42 _(n) and 44 ₁-44 _(n), the inductor component 18, and a circuit board 46 to which the components 18, 42, and 44 are mounted.

The transistor components 42 ₁-42 _(n) respectively include the high-side drive transistors 14 ₁-14 _(n) of FIG. 1, and the transistor components 44 ₁-44 _(n) respectively include the low-side drive transistors 16 ₁-16 _(n) of FIG. 1. The transistor components 42 ₁-42 _(n) and 44 ₁-44 _(n) may be similar to the transistor component 30 of FIGS. 2A-2C.

The corresponding leads of each high-side/low-side pair of transistor components 42 and 44 are coupled to a respective conductive trace 48 on the circuit board 46, where the conductive trace corresponds to a respective node INT of FIG. 1. For example, the source leads S of the transistor component 42 ₁ and the drain leads D of the transistor component 44 ₁ are soldered to the trace 48 ₁ (corresponds to the node INT₁ of FIG. 1), the source leads S of the transistor component 42 ₂ and the drain leads D of the transistor component 44 ₂ are soldered to the trace 48 ₂ (corresponds to the node INT₂ of FIG. 1), and so on. Alternatively, because of the direction of the phase currents i₁-i_(n) when the low-side transistors 16 ₁-16 _(n) are on, the source leads S of the low-side transistor components 44 ₁-44 _(n) (instead of the drain leads D of the low-side transistor components) may be soldered to the respective traces 48 ₁-48 _(n).

The inductor component 18 includes a package 50, which is shown in phantom dashed line, the inductors L₁-L_(n), which are disposed inside of the package and which are omitted from FIGS. 3A-3B for clarity, and conductive leads 52 ₁-52 _(n) and 54.

The package 50 includes an upper surface 56, which faces away from the circuit board 46, and a lower surface 58, which faces toward the circuit board. The package 50 may be formed from plastic, ceramic, or any other suitable material.

Protruding from the lower surface 56 are supports (hereinafter standoffs) 60 ₁ and 60 ₂, which together with the lower surface, form a recess 62, which receives, at least partially, the transistor components 42 and 44. That is, a depth d of the recess 62 is greater than or equal to the height h of the transistor components 42 and 44 so that the when the inductor component 18 is positioned over the transistor components 42 and 44, the standoffs 60 ₁ and 60 ₂ contact the circuit board 46, and thus support the inductor component over the transistor components. Therefore, the standoffs 60 ₁ and 60 ₂ allow one to stack the inductor component 18 and the transistor components 42 and 44.

Each of the leads 52 ₁-52 _(n) is coupled to the drive node (the node respectively corresponding to the node INT₁-INT_(n) of FIG. 1) of a respective inductor L₁-L_(n), and is soldered to a respective trace 48 ₁-48 _(n). The leads 52 ₁-52 _(n) may also act as standoffs.

In contrast, the lead 54 is coupled to the output nodes of all of the inductors L₁-L_(n), and is soldered to a circuit-board trace (not shown in FIGS. 3A and 3B) that is connected to the filter inductor 26 if the filter inductor is present or to the node providing V_(out) if the filter inductor is omitted. Like the leads 52 ₁-52 _(n), the lead 54 may also act as a standoff.

In an embodiment of the power-supply portion 40, the height of the inductor component 18 measured at its upper surface 56 may be less than or equal to about 4 mm, which may be low enough for many power-supply applications.

Still referring to FIGS. 3A-3B, alternate embodiments of the power-supply portion 40 and the inductor component 18 are contemplated. For example, although shown as covering only parts of the transistor components 42 and 44, the inductor component 18 may completely cover some or all of the transistor components, or may not cover any portion of some of the transistor components. Furthermore, although shown disposed at the ends of the package 50, the standoffs 60 ₁ and 60 ₂ may be disposed at other locations (e.g., the center) of the package. Moreover, although two standoffs 60 ₁ and 60 ₂ are shown, the package 50 may include more or fewer than two standoffs. In addition, the leads 52 and 54 may be disposed at locations of the package other than the illustrated locations. For example, the leads 52 ₁-52 _(n) may each protrude from the lower surface 58 over a respective one of the traces 48 ₁-48 _(n). Furthermore, although the inductor component 18 is described as being stacked over the transistor components 42 and 44, the transistor components may be stacked over the inductor component 18 in a similar manner, or, in general, any first component may be stacked over any second component in a similar manner. Moreover, more than two components may be stacked over one another. In addition, the space between the lower surface 58 of the inductor-component package 50 and the circuit board 46 (and between the lower surface of the package and the transistor components 42 and 44 if d>h) may be partially or completely filled with a material such as epoxy or a thermally conductive material. Furthermore, although discussed as including inductors and transistors, respectively, the components 18, 42, and 44 may also include other circuit elements. Moreover, the dimensions of the inductor component 18 and the transistor components 42 and 44 may be different than disclosed.

FIG. 4 is a side view of another embodiment of the power-supply portion 40 of FIGS. 3A and 3B including another embodiment of the inductor component 18. The inductor component 18 of FIG. 4 includes a package 70 and standoffs 72 ₁ and 72 ₂, and is similar to the inductor component 18 of FIGS. 3A and 3B except that unlike the standoffs 60 ₁ and 60 ₂, which are integral with the package 50, the standoffs 72 ₁ and 72 ₂, are attached to the package 70. For example, the standoff's 72 ₁ and 72 ₂ may be made of metal and attached the sides of the package 70, or they may be part of and extend from a lead frame (not shown in FIG. 4) internal to the package 70. Alternatively, the standoffs 72 ₁ and 72 ₂ may be conductive leads that are respectively coupled to the inductors L₁-L_(n) or to other circuit elements within the package 70. For example, the output lead 54 (FIGS. 3A and 3B) may form the standoff 72 ₁.

Alternate embodiments of the power-supply portion 40 and the inductor component 18 of FIG. 4 are contemplated. For example, the alternate embodiments discussed above in conjunction with FIGS. 3A and 3B are contemplated for the power-supply portion 40 and inductor component 18 of FIG. 4.

FIG. 5 is a side view of another embodiment of the power-supply portion 40 of FIG. 3A including another embodiment of the inductor component 18. The inductor component 18 of FIG. 5 is similar to the inductor component 18 of FIGS. 3A and 3B except that the component 18 of FIG. 5 also includes a heat sink 80 attached to the upper surface 56 of the package 50 with, e.g., a thermally conductive adhesive. Furthermore, any space 82 between the lower surface 58 of the package 50 and the transistor components 42 and 44 and the circuit board 46 may be filled with a thermally conductive material such that the heat sink 80 is operable not only to dissipate heat generated by the inductors L₁-L_(n) (not shown in FIG. 5), but is also operable to dissipate heat generated by the transistor components and any other components (not shown in FIG. 5) over which the inductor component 18 is disposed. The heat sink 80 may be made from metal or from any other heat-conductive material.

Alternate embodiments of the power-supply portion 40 and the inductor component 18 of FIG. 5 are contemplated. For example, the heat sink 80 may have a different shape or pattern than disclosed in conjunction with FIG. 5. Furthermore, the heat sink 80 may be attached to the package 50 in any conventional manner other than with an adhesive, and may be attached to the sides of the package in addition to or instead of to the upper surface 56. Moreover, a thermo-electric cooler (Le., a Peltier device) may be disposed between the heat sink 80 and the package 50 (hot side of the thermo-electric cooler toward the heat sink, cool side toward the package) such that that combination of the heat sink and cooler may dissipate more heat from the inductor component 18 than the heat sink alone. In addition, the heat sink 80 may be attached to the upper surface 56 of the package 70 of FIG. 4 to form another embodiment of the inductor component 18. Furthermore, the alternate embodiments discussed above in conjunction with FIGS. 3A, 3B, and 4 for the power-supply portion 40 and the inductor component 18 are also contemplated for the power-supply portion 40 and the inductor component 18 of FIG. 5.

FIG. 6 is a side view of another embodiment of the power-supply portion 40 of FIG. 3A including another embodiment of the inductor component 18. The inductor component 18 of FIG. 6 is similar to the inductor component 18 of FIGS. 3A and 3B except that the inductor component of FIG. 6 includes a package 90 having an upper surface 92 that is patterned to have an increased area (as compared to the area of the lower surface 58) for the increased dissipation of heat. That is, the package 90 acts as a heat sink. Furthermore, any space 82 between the lower surface 58 of the package 90 and the transistor components 42 and 44 and the circuit board 46 may be filled with a thermally conductive material such that the package 90 is operable not only to dissipate heat generated by the inductors L₁-L_(n) (not shown in FIG. 6), but is also operable to dissipate heat generated by the transistor components. The package 90 may be made from plastic or from any other suitable heat-conductive material.

Alternate embodiments of the power-supply portion 40 and the inductor component 18 of FIG. 6 are contemplated. For example, the upper surface 92 of the package 90 may have a different pattern or shape than that disclosed in conjunction with FIG. 6. Furthermore, the sides of the package 90 may also be patterned to increase their surface areas. Moreover, the upper surface 56 of the package 70 of FIG. 4 may be patterned to increase the area of the surface 56 and improve the heat dissipation rate of the package, and to thus form another embodiment of the inductor component 18. In addition, the alternate embodiments discussed above in conjunction with FIGS. 3A, 3B, 4, and 5 for the power-supply portion 40 and for the inductor component 18 are also contemplated for the power-supply portion 40 and the inductor component 18 of FIG. 6.

FIG. 7 is a perspective view of a portion 100 of an embodiment of the power supply 10 of FIG. 1, in which another embodiment of the inductor component 18 spans only a single pair of transistor components 42 and 44. For brevity, only the transistor components 42 and 44 and inductor component 18 of a single power-supply phase are shown, it being understood that for the power supply 10 having multiple phases, the layouts of the other inductor components relative to the other high-side/low-side transistor-component pairs may be similar.

The inductor component 18 includes a package 102 having upper and lower surfaces 56 and 58, and standoffs 104 ₁ and 104 ₂, which are similar to the standoffs 72 ₁ and 72 ₂ of FIG. 4. In one embodiment, the standoff 104 ₁ also forms an output lead that is coupled between an output node of the inductor L (not shown in FIG. 7) within the package 102 and V_(out) (or the filter inductor 26 if present), and the standoff 104 ₂ also forms an input lead that is coupled between an input node of the inductor L and the source of the transistor 14 ₁ (not shown in FIG. 7) in the transistor component 42 and the drain of the transistor 16 ₁ (not shown in FIG. 7) in the transistor component 44. The conductive traces on the circuit board 46 to which the standoffs/leads 104, and 104 ₂ are respectively soldered are omitted from FIG. 7 for clarity.

Alternate embodiments of the power-supply portion 100 and the inductor component 18 of FIG. 7 are contemplated. For example, the standoffs 104 ₁ and 104 ₂ may be replaced with standoffs similar to the standoffs 60 ₁ and 60 ₂ of FIG. 3A, and the inductor leads may extend from the standoffs or from other portion of the package 102. In addition, the alternate embodiments discussed above in conjunction with FIGS. 3A, 3B, 4, 5, and 6 for the power-supply portion 40 and for the inductor component 18 are also contemplated for the power-supply component 100 and the inductor component 18 of FIG. 7.

FIG. 8 is a block diagram of a system 110 (here a computer system), which may incorporate a single-phase or multiphase power supply 112 (such as the power supply 10 of FIG. 1) that includes one or more of the embodiments of the power-supply portion 40 or of the inductor component 18 of FIGS. 3A-7.

The system 110 includes computer circuitry 114 for performing computer functions, such as executing software to perform desired calculations and tasks. The circuitry 114 typically includes a controller, processor, or one or more other integrated circuits (ICs) 116, and the power supply 112, which provides power to the IC(s) 116. One or more input devices 118, such as a keyboard or a mouse, are coupled to the computer circuitry 114 and allow an operator (not shown) to manually input data thereto. One or more output devices 120 are coupled to the computer circuitry 114 to provide to the operator data generated by the computer circuitry. Examples of such output devices 120 include a printer and a video display unit. One or more data-storage devices 122 are coupled to the computer circuitry 114 to store data on or retrieve data from external storage media (not shown). Examples of the storage devices 122 and the corresponding storage media include drives that accept hard and floppy disks, tape cassettes, compact disk read-only memories (CD-ROMs), and digital-versatile disks (DVDs).

From the foregoing it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the description. Furthermore, where an alternative is disclosed for a particular embodiment, this alternative may also apply to other embodiments even if not specifically stated. 

What is claimed is:
 1. A method, comprising: placing a first component over a circuit board; and placing a first portion of a second component over the first component such that a second portion of the second component contacts the circuit board, and such that the first and second portions of the second component define a space within which is located the first component.
 2. The method of claim 1 wherein placing the first component comprises placing the first component in contact with the circuit board.
 3. The method of claim 1, further comprising at least partially filling a space between the first component and the first portion of the second component with a thermally conductive material.
 4. The method of claim 1 wherein placing the first and second components comprises soldering the first component and the second portion of the second component to the board.
 5. The method of claim 1 wherein: placing the first component comprises coupling a lead of the first component to a conductive path disposed on the circuit board; and placing the second component comprises coupling a lead of the second component to the conductive path. 